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		<H3><A name="HDRTRACE" ></A>Trace</H3>
		<A NAME="IDX745"></A><A NAME="IDX746"></A>
<P><STRONG>Category</STRONG>
<P>
<A HREF="refgu008.htm#HDRCATDBG">Debugging</A>
<P><STRONG>Function</STRONG>
<P>
Enable or disables tracing options.
<P><STRONG>Syntax</STRONG>
<PRE>
Trace(<STRONG>what, how</STRONG>);
</PRE>
<P><STRONG>Inputs</STRONG>
<BR>
<TABLE BORDER>
<TR>
<TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Name
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Type
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Default
</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">Description
</TH></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>what</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">string
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">none
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">the object to be traced
</TD></TR><TR>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>how</STRONG></TT>
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">integer
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">1
</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">0: set tracing off
<BR>
1: set tracing on
</TD></TR></TABLE>
<P><STRONG>Functional Details</STRONG>
<P>
<TABLE CELLPADDING="3">
<TR VALIGN="TOP"><TD><P><B><TT><STRONG>what</STRONG></TT>
</B></TD><TD><P>is (1) a keyword specifying the object to be traced <I>or</I>
(2) a set of letters specifying a group
of debug message classes, as used by the
<TT><STRONG>DXEnableDebug()</STRONG></TT>
library function (see <I>IBM Visualization Data Explorer Programmer&#39;s
Reference</I>).
<P>
At present, the only keyword value allowed for this parameter is
<TT><STRONG>"time"</STRONG></TT>:
<TT><STRONG>Trace("time", 1);</STRONG></TT> will begin the trace, and
<TT><STRONG>Trace("time", 0);</STRONG></TT> will print a record of time use
since the tracing was started.
The output appears in the Message window.
<BR>
If <TT><STRONG>what</STRONG></TT> is a string of lowercase letters other than
<TT><STRONG>time</STRONG></TT>, the module calls the
<TT><STRONG>DXEnableDebug</STRONG></TT> library
function.
(The uppercase letters A-Z and the numbers 0-9 are reserved
for system use).
</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>how</STRONG></TT>
</B></TD><TD><P>specifies whether the trace option is activated or not.
</TD></TR></TABLE>
<P><B>Note: </B>If the executive is started with the flag <TT>-timing</TT> on,
the command <TT>Trace(&quot;time&quot;, 0)</TT> causes all module
entry and exit times to be printed.
In the VPE window, this command can be

enabled using the Debug Tracing button
in the <TT><STRONG>Commands</STRONG></TT> menu of the

Message window (see
<A HREF="usrgu046.htm#HDRDEBUG">8.2 , "Using the Message Window"</A> in <I>IBM
Visualization Data Explorer User&#39;s Guide</I>).
<P><STRONG>Script Language Example</STRONG>
<P>
In this example, the module traces the use of time by Isosurface.
<PRE>
electrondensity = Import("/usr/local/dx/samples/data/watermolecule");
electrondensity = Partition(electrondensity);
camera = AutoCamera(electrondensity, width=5);
Trace("time", 1);
isosurface = Isosurface(electrondensity, 0.3);
Trace("time", 0);
Display(isosurface, \camera);
</PRE>
<P><STRONG>See Also</STRONG>
<P>
&nbsp;<A HREF="refgu166.htm#HDRUSAGE">Usage</A>
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